Help with 4X4 not engaging

jlambert58 · #1 (**permalink**) 12-07-2007, 03:46 PM

New to his site...

Please help - any/all information would be great.

My (new to me) 2003 F-150 FX4 5.4/auto 77K miles with esof does not engage the front axle regularly. It doesn't seem to matter if I go to 4H or 4L. The lights on the dash come on properly, but the front axle doesn't pull. It works sometimes, and doesn't other times. I just sold my 1997 F-150 esof that worked flawlessly for 200K + miles.

Also, wondering if the differentials should "Lock-up"? Meaning - should all 4 wheels spin if stuck in the mud/snow? Seems like my old 97 did....

sled_ers_rus · #2 (**permalink**) 06-14-2008, 09:07 PM

i have the exact same problem with my 03 fx4. from what ive heard if your front drive shaft turns/works properly and your vaccum actuator on the axle goes back and forth, like mine, and still no pulling power, its supposedly some sort of bushing in the axle.? thats what i was told

ncranchero · #3 (**permalink**) 06-15-2008, 06:56 AM

Generally it will be 1 of 3 issues.
1- Bad solenoid on the firewall
2- Bad vacuum line to the disconnect diaphragm
3- Bad or stuck disconnect diaphragm

There are a lot of posts on this problem, many from my experiences trying to diagnose/repair mine. Start here http://www.ford-trucks.com/forums/62...nt-engage.html
and then click the "search" tab at the top of the page to look for the rest of the posts. Use the Advanced Search feature and enter "vacuum" under keyword and my user name and you'll get a list to view. I also have some photos/diagrams in my GALLERY under TECH. Let us know if you need more help.

ncranchero · #4 (**permalink**) 06-15-2008, 07:05 AM

Quote:

Originally Posted by sled_ers_rus

i have the exact same problem with my 03 fx4. from what ive heard if your front drive shaft turns/works properly and your vaccum actuator on the axle goes back and forth, like mine, and still no pulling power, its supposedly some sort of bushing in the axle.? thats what i was told

WOW that was an old post I responded to before I realized it was 6 months old! But yes, if all of the vacuum components are working properly the shift fork is possibly bad. That would be # 13 in this illustration from FORD.